How to Fix Disappearing Views When the Keyboard Appears in Xcode 6? - swift

Question

I've included a link to a video that shows what problem I'm having:
https://dl.dropboxusercontent.com/u/39330138/Bug_Demo1.mov
There are two View Controllers, the first is non blurred and less important. When the plus button is clicked, the app segues to a new controller (without animating) and in prepareForSegue() I use UIGraphicsBeginImageContext and UIGraphicsGetImageFromCurrentImageContext to capture a UIImage from the current view and pass it on to the next one.
When the new view appears I use UIVisualEffectView to create a blur view and add it as a subview to the Image View that is the 'background'. Then, its opacity is animated at the same time the 2 views and 2 buttons are animated on screen with UIView animation and springWithDamping, giving the illusion of the view blurring over and items animating over the top.
The top view has a UITextField embedded in it which, when tapped calls becomeFirstResponder() and makes all overlaid (New Session, Tag & Button) views including the Visual Effect View imbedded in the background Image View disappear.
The reason I go into so much detail is because I'm not sure what exactly the problem is. However, I have a suspicion that it is to do with the AutoLayout/Size Classes in Xcode 6.
Does anyone know why this might be happening and how to fix it?
If you need additional information, just let me know.
Thanks!
EDIT:
When I log the views after I click on the TextField, all the frames seem the same.
EDIT 2:
Here's a link to a demo project will all the functionality from the video:
https://dl.dropboxusercontent.com/u/39330138/DEMO%20APP.zip

Answer 1

There are a couple of things happening here, but the main culprit is your use of viewDidLayoutSubviews(). This is called any time the system has to reevaluate the layout. I see you're setting your UIVisualEffectView's alpha to 0 in that method:
if !returningFromTagView {
blurView.alpha = 0
}
I think you're intending this to be called just once before the view appears because I see you animate the alpha to 1 in viewDidAppear(animated: Bool). However, any time the system reevaluates layout for any reason, viewDidLayoutSubviews() is called and the alpha on blurView is going back to 0 if returningFromTagView is false. That's why when you summon the keyboard (triggering a layout reevaluation), this view disappears. Xcode also warns you about making the alpha 0 in the console (it breaks the visual effect until the opacity returns to 1). Put the code above in the viewDidLoad() method instead, and you'll see blurView come back. The alpha only needs to be set to 0 once when the view loads.
The issue with the other views is a bit tougher to see, but the culprit again is your use of viewDidLayoutSubviews(). I imagine that you're puzzled why the views don't appear even after you've been very thorough in your keyboardNotfication() method to set the frames, bring the views to the front, make sure they aren't hidden, and then log this all. But after the keyboardNotification() method finishes, the layout system once again is triggered, and I see that you're nudging the views' frames here and there:
if returningFromTagView {
setX(-titleView.frame.size.width, v: titleView)
setX(-tagView.frame.size.width, v: tagView)
setX(-(cancelButton.frame.size.width + 20 + nextButton.frame.size.width), v: cancelButton)
setX(-nextButton.frame.size.width, v: nextButton)
} else {
setX(-titleView.frame.size.width, v: titleView)
setX(view.frame.size.width, v: tagView)
setX(-cancelButton.frame.size.width, v: cancelButton)
setX(view.frame.size.width, v: nextButton)
}
You're moving the views offscreen every time a layout change is made! Pause the program after you summon the keyboard and look at your view hierarchy using Xcode 6's great new Capture View Hierarchy ability. It's in Debug > View Debugging > Capture View Hierarchy. Those views are just hiding off to the side.
I image you're trying to do this just once when the view appears in order to support your transition animations, but it gets called whether the view is just appearing or if a small change like the keyboard is appearing. I suggest that you implement these animations another way, like using the views' transforms or using autolayout constraints (though you have a lot of missing constraints in the storyboard) to do your animation. viewDidLayoutSubviews() is really a place to fudge things here and there in your layout after the layout system has done its work. You should have a good reason for using it. It has the nice feature of overriding your autolayout constraints and letting you animate those views without toying with the constraints (because the method happens after the updateConstraints() and layoutSubviews() methods), and that's why we can't put the above code in a method like viewWillAppear(animated: Bool) instead (because autolayout constraints would counter the animation during layout later), but viewDidLayoutSubviews() just is not a method that's meant to support basic animations.
In spite of that, here's something simple to get your app going again and for you to see what's going on:
Make a property var comingFromSessionView: Bool property for your NewSessionVC view controller. In the prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) of SessionVC, add nextVC.comingFromSessionView = true
Then change the code block from viewDidLayoutSubviews() above to this:
if returningFromTagView {
setX(-titleView.frame.size.width, v: titleView)
setX(-tagView.frame.size.width, v: tagView)
setX(-(cancelButton.frame.size.width + 20 + nextButton.frame.size.width), v: cancelButton)
setX(-nextButton.frame.size.width, v: nextButton)
} else if comingFromSessionView {
setX(-titleView.frame.size.width, v: titleView)
setX(view.frame.size.width, v: tagView)
setX(-cancelButton.frame.size.width, v: cancelButton)
setX(view.frame.size.width, v: nextButton)
}
We'll switch these Bools to false during viewDidAppear after it's done with them:
override func viewDidAppear(animated: Bool) {
...
if returningFromTagView {
...
returningFromTagView = false
} else if comingFromSessionView {
...
comingFromSessionView = false
}
}
Now when the keyboard is summoned, your views are right where you left them!
The code above isn't great. I'd rather stay away from viewDidLayoutSubviews() for doing these animations. But hopefully you can see what's going on now. Your viewsDidLayoutSubviews() has been whisking away your views.